Analyzing and mapping ECG signals and determining ablation points to eliminate brugada syndrome

ABSTRACT

A system and method for Brugada syndrome epicardial ablation comprising preparing an endocardial duration map; preparing a baseline epicardial duration map comprising at least one or more areas of delimination; and when some of the areas of delimination are greater than 200 ms, performing epicardial ablation of the areas of delimination greater than 200 ms. The method may further comprise preparing an updated epicardial duration map after performing epicardial ablation, and determining whether or not a BrS pattern appears in the updated epicardial duration map; and when the BrS pattern appears, performing epicardial ablation. The method may further comprise preparing an updated epicardial duration map after performing epicardial ablation, and determining whether or not an abnormal EGM exists in the updated epicardial duration map; and when the abnormal EGM exists, performing epicardial ablation. The method may further comprise preparing an updated epicardial map comprising maintaining anatomical volume data and adding electroanatomical data.

CROSS REFERENCE TO RELATED APPLICATION

This application incorporates by reference as if fully set forth U.S.patent application Ser. No. 15/854,492 filed on Dec. 26, 2017 titled “AMethod And System For Eliminating A Broad Range Of Cardiac Conditions ByAnalyzing Intracardiac Signals, Providing A Detailed Map And DeterminingPotential Ablation Points”. This application claims the benefit of U.S.Provisional Application No. 62/450,388, filed on Jan. 25, 2017. Thisapplication is a Continuation in Part of U.S. patent application Ser.No. 15/854,485, filed on Dec. 26, 2017 which is incorporated byreference as if fully set forth.

SUMMARY

There is provided according to embodiments of a system and method thatenables improved analysis of electrocardiography (ECG) signals toeliminate Brugada syndrome. (BrS) The system and method can create apotential duration map (PDM) by automatically measuring duration ofsignals and annotating ventricular eletrogram (EGM) duration from onsetto offset.

The method of Brugada syndrome epicardial ablation may comprisepreparing an endocardial duration map, preparing a baseline epicardialduration map comprising at least one or more areas of delimination, andwhen some of the areas of delimination are greater than 200 ms,performing epicardial ablation of the areas of delimination greater than200 ms. The method may further comprise preparing an updated epicardialduration map after performing epicardial ablation, and determiningwhether or not a BrS pattern appears in the updated epicardial durationmap; and when the BrS pattern appears, performing epicardial ablation.The method may further comprise preparing an updated epicardial durationmap after performing epicardial ablation, and determining whether or notan abnormal EGM exists in the updated epicardial duration map; and whenthe abnormal EGM exists, performing epicardial ablation. The method mayfurther comprise preparing an updated epicardial map comprisingmaintaining anatomical volume data and adding electroanatomical data.The method may further comprise the baseline epicardial duration map,and the updated epicardial map displaying concentric areas havingcut-off intervals. The method may further comprise, in the step ofpreparing a baseline epicardial duration map, defining a window ofinterest (WOI) comprising at least a cycle length, calculating previousheart beats based on the cycle length and reference annotation,assigning the heart beats within the cycle length of the WOI to the WOI,finding a start potential duration and an end potential duration, andselecting an ablation point based on a heart beat having a minimumstandard deviation from the heart beats assigned to the WOI.

The system for Brugada syndrome epicardial ablation in a heart maycomprise a catheter for measuring ECG signals, a computer adapted to:prepare an endocardial duration map; prepare a baseline epicardialduration map comprising at least one or more areas of delimination; andwhen one or more of the areas of delimination are greater than 200 ms,performing epicardial ablation of the areas of delimination greater than200 ms; and a display device for displaying the endocardial duration mapand the baseline epicardial map. The computer in the system may furtherbe adapted to prepare an updated epicardial duration map afterperforming epicardial ablation, and determine whether or not a BrSpattern appears in the updated epicardial duration map, and when the BrSpattern appears, perform epicardial ablation. The computer in the systemmay further be adapted to prepare an updated epicardial duration mapafter performing epicardial ablation, and determine whether or not anabnormal EGM exists in the updated epicardial duration map, and when theabnormal EGM exists, perform epicardial ablation. The system may furthercomprise a tool for injecting ajmaline into the heart. The computer inthe system may further be adapted to prepare an updated epicardial mapafter performing epicardial ablation, comprising maintaining anatomicalvolume data and adding electroanatomical data. The computer in thesystem may further be adapted to display concentric areas having cut-offintervals on the baseline epicardial duration map and the updatedepicardial map. The computer in the system may further be adapted toprepare the baseline epicardial duration map by performing steps ofdefining a WOI comprising at least a cycle length, calculating previousheart beats based on the cycle length and reference annotation,assigning the heart beats within the cycle length of the WOI to the WOI,finding a start potential duration and an end potential duration, andselecting an ablation point based on a heart beat having a minimumstandard deviation from the heart beats assigned to the WOI.

A computer program product for Brugada syndrome epicardial ablation isalso presented.

These and other objects, features and advantages of the presentinvention will be apparent from the following detailed description ofillustrative embodiments thereof, which is to be read in connection withthe accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

For a better understanding of the present invention, reference is madeto the detailed description of the invention, by way of example, whichis to be read in conjunction with the following drawings, wherein likeelements are given like reference numerals.

FIG. 1 shows a Potential Duration Map (PDM).

FIG. 2 is a flow diagram of an example method in an embodiment.

FIGS. 3A, 3B, 3C show Brugada syndrome concentric substratedistribution.

FIGS. 4A, 4B show a PDM before and after radiofrequency ablation.

FIG. 5 shows a calculation of potential duration.

FIG. 6 shows changes in BS ECG signal.

FIG. 7 is a work flow diagram of Brugada syndrome epicardial ablation inone embodiment.

FIG. 8 shows an example mapping system for real-time mapping of cardiacablation in accordance with an embodiment, in which the inventivetechnique is used.

FIG. 9 is a block diagram illustrating example components of a medicalsystem in one embodiment.

FIGS. 10A, 10B, 10C illustrate test results for one example patient.

FIG. 11 illustrates additional test results for one patient.

FIG. 12 shows a spontaneous type 1 Brugada pattern for one patient.

FIG. 13 shows RF ablation in spontaneous type 1 Brugada pattern for onepatient.

FIG. 14 shows a PDM before and after RF ablation for an example patient.

FIG. 15 shows ECG changes for the example patient.

FIG. 16 shows a table of ablation results for the example patient.

FIG. 17 shows a table of electrophysiological characteristics of studypopulation.

DETAILED DESCRIPTION OF THE INVENTION

Brugada syndrome (BrS) is an ECG abnormality with a high incidence ofsudden death in patients with structurally normal hearts. This syndromeor disorder is characterized by sudden death associated with one ofseveral ECG patterns characterized by incomplete right bundle-branchblock and ST-segment elevations in the anterior precordial leads.

BrS is a genetically determined disease predisposing to sudden cardiacdeath due to ventricular malignant arrhythmias. A first aspect of thepresent system and method is treating Brugada syndrome by analyzing theEGM signals, determining the ablation points, and manually editing thecalipers on the mapping catheter to set the duration. A second aspect ofthe present system is an example method, presented below, which enablesvisualization of the abnormal substrate according to the EGMs' durationfound on the epicardial layer of BrS patients.

FIG. 1 shows a Potential Duration Map (PDM) (e.g., RV epicardial Map),in the center, a selected point viewer in the left column, and Pasoviewer in the right column. The PDM uses a scale of Shortex ComplexInterval (SCI) which ranges from 15.0 ms to 171.0 ms. The PDM is createdusing the present system to measure the Potential Duration for eachpoint that the EGM automatically creates in accordance with the mappingmethod. The EGM shown in FIG. 1, left side, includes MAP1-2 and MAP3-4,each having peaks 101 that indicate changes in direction of the tracingsof the mapping catheter.

The example method is performed to visualize the abnormal substrateaccording to the EGMs duration found on the epicardial layer of BrSpatients. Using, for example, the Complex Fractionated AtrialElectrograms (CFAE) module of the CARTO® 3 system (Biosense Webster),for each electroanatomical acquired point, two calipers are manuallymoved by placing the first on the onset and the second on the offset ofthe EGM recorded. Note that CFAE performs calculations using thefragmentation in Bipolar EGM signal in the acquired point. Thefragmentation is marked as interval duration with left and rightborders. The present method results in the exact measurement of theventricular EGM duration, enabling the creation of a PDM that maycomprise a coded mapping, such as a color-coded map (color shown usingdifferent hatching patterns), showing different degrees of prolongation.The appropriate characterization of the abnormal substrate along withthe localization of such EGMs helps to establish the appropriate targetfor catheter ablation in order to achieve a successful procedure, andthe PDM enables such characterization.

As shown in FIG. 1, the present system can be used to automaticallyannotate and measure EGM signals (as shown in the left panel) to createthe PDM for Brugada syndrome elimination by ablation. This system usesan annotation technique to improve conventional software, such as CARTO®3, by automating the process of detecting where to ablate.

FIG. 2 is a flow diagram of an example method for automaticallydetermining ablation points in Brugada syndrome. As shown in FIG. 2, themethod is performed as follows.

In step S201, a Window Of Interest (WOI) is defined, the WOI being theinterval in the EGM and/or ECG which is normally used to calculate thevoltage amplitude (peak to peak mV) and the signal duration. An exampleEGM is shown in FIG. 1.

In step S202, at least two previous heart beats are calculated based oncycle length and reference annotation, and a WOI is assigned for two ofthe heart beats. Note that each electroanatomical acquired point (e.g.,point EGM) contains data to be used for coloring the Map according toMap Type, such as PDM, CFAE, LAT, Bipolar Voltage etc. Example maps areshown in FIGS. 10-14, (described hereinafter). In one acquired point,for example, a window equal to 2500 ms of ECG and EGM is recorded. Forexample, if the reference annotation for a heart beat lays at 2000 ms,the first WOI [−50 ms, 350 ms] goes from 2000 ms−50 ms (e.g., 1950 ms)to 2000 ms+350 ms (e.g., 2350 ms). If the heart beat cycle length is 800ms, there is more than one heart beat in the 2500 ms WOI. The previousheart beat reference lays at 1200 ms (2000 ms−800 ms [e.g., 1200 ms])and the WOI will be from 1200 ms−50 ms (e.g., 1150 ms) to 1200 ms+350 ms(e.g., 1550 ms). It should be noted that the abovementioned timeintervals have been used by way of example and should not be consideredas limiting.

Next, for each WOI of each heart beat, the Potential Duration iscalculated as shown in steps S203-211, as follows.

In step S203, the peaks are calculated based on a predeterminedthreshold in WOI and a list of peaks in WOI are created. The EGM signalvalues are measured in mV, and, in one example, a peak with mV valuegreater than 0.05 mV is marked. However, it should be noted that thepeak threshold may be set by the physician.

In step S204, Potential Duration Start (PD-Start) is defined by checkingfrom the beginning of the WOI, as shown in steps S205-S207 as follows.

In step S205, it is determined whether or not two consecutive peaks havethe same sign and the same peaks absolute values are less than 2*Min.

In step S206, if S205=YES (two consecutive peaks have the same sign andthe absolute value of the consecutive peaks is less than 2*Min), thecurrent peak is set as the second peak, the next peak is obtained andthe method returns to step S205.

In step S207, if S205=NO (two consecutive peaks do not have the samesign and/or the absolute value of the consecutive peaks is greater thanor equal to 2*Min), the start of the slope before the current peak isfound and marked it as Start potential duration.

In step S208, Potential Duration End (PD-END) is defined, checking fromthe ending of the WOI, as shown in steps S209-S210 as follows.

In step S209, it is determined whether or not two consecutive peaks'distance is greater than 120 ms.

In step S210, if S209=YES (two consecutive peaks are greater than 120ms), the start of PD-End portion is marked as the peak with minimum timeof the two consecutive peaks and the method returns to step S209.

In step S211, if S209=NO (two consecutive peaks do not have distancegreater than 120 ms), then in step S211, it is determined whether twoconsecutive peaks have the same sign and the peaks' absolute values areless than 2*Min Threshold, whether the time between two consecutivepeaks is greater than 120 ms or whether the time between two consecutivepeaks is less than 25 ms.

Keeping in mind that the stability and reproducibility of the durationof the potential can be a crucial factor, in one embodiment, the presenttechnique can consider another factor; the technique can verify, in thepresence of a double or late potential, that the late activity is alsopresent in all the beats included in the 2500 ms recording window.

In step S212, if S211=YES (two consecutive peaks have the same sign andthe peaks' absolute values are less than 2*Min, the time between twoconsecutive peaks is greater than 120 ms or the time between twoconsecutive peaks is less than 25 ms), the next peak is obtained withminimum time, and the method returns to step S211.

In step S213, if S211=NO (two consecutive peaks do not have the samesign, the peaks absolute values are equal to or greater than 2*Min orthe time between two consecutive peaks is less than or equal to than 120ms or the time between two consecutive peaks is greater than or equal to25 ms), the start of the slope after the current peak is found andmarked as End Potential Duration.

In step S214, the Potential Duration value is calculated as thedifference between potential duration Start and potential duration Endin ms.

In step S215, the selected point potential duration value is set as theheart beat which has the minimum standard deviation of the positions oneach heart beat WOI. Note that the area measurement between the BS ECGIS when inducing the BrS and the BS ECG IS after treating the BrS canprovide the indication of when to stop the procedure.

In accordance with the PDM and the analysis described above, any EGMshowing a duration ≥200 ms may be considered abnormal, and thusrepresents a target for catheter ablation. Three different concentricareas are identified according to the degree of prolongation by settingdifferent cut-off intervals, for example, ≥300 ms, ≥250 ms and ≥200 ms,respectively. The different cut-offs are necessary to guide the ablationprocedure, starting from the small “core” of the substrate (area showingEGM duration ≥300 ms) and subsequently moving to the larger regionshaving potential duration ≥250 ms and ≥200 ms, respectively, as shown inFIGS. 3A, 3B and 3C, described in more detail below.

The inventive technique may enable the elimination of all delayed andprolonged EGM activities located in the abovementioned regions. Class ICdrug challenge is performed at the end of ablation in order to ensuresuccessful abolition of all abnormal potentials and stable BrS-ECGpattern elimination. In cases of BrS-ECG pattern reappearance after drugchallenge, the epicardial PDM is a remap of the epicardial using PDM toidentify target locations with PDM bigger than 200 ms for ablation. Thisis repeated to identify any residual or additional abnormal signals forfurther RF applications in order to completely normalize the ECGpattern. The final end-point, e.g., ablation point, is obtained by theelimination and the non-inducibility of the BrS ECG pattern proved bythe Class IC drug test and the abolition, using RF catheter ablation, ofany prolonged and fragmented potential identified during the mappingprocedure.

FIGS. 3A, 3B and 3C show Brugada Syndrome concentric substratedistribution, that is, each of these figures show an epicardial PDMafter Class IC drug-challenge. The maps are reconstructed by collectingthe duration of each bipolar EGM. The color-code (shown as differenthatching patterns) ranges from red 301 to purple 305, where red 301 isshowing regions exhibiting less than 110 ms duration. Purple 305 isrepresenting areas with longer EGM duration (≥300 ms in FIG. 3A, ≥250 msin FIG. 3B and ≥200 ms in FIG. 3C). Additional colors (not shown)represent areas ≥110 ms to 300 ms. According to the different cut-offapplied, a concentric distribution is shown, where the longestpotentials (≥300 ms duration) are located in the inner circle (FIG. 3A),whilst the relatively shorter ones, but still ≥200 ms, are in the outercircle (FIG. 3C). The regions showing longer potential duration havedifferent dimensions (≥300 area is 5.9 cm², ≥250 area is 14.7 cm² and≥200 ms area is 27.6 cm², respectively). Below each map in FIGS. 3A, 3B,3C, an example of the EGM recorded in the purple 305 area when thecoved-type pattern occurs after ajmaline test is shown (EGMs of 322 ms,255 ms and 230 ms duration in each panel of FIG. 3A, 3B, 3C,respectively).

The QRS complex is a name for the combination of three of the graphicaldeflections seen on a typical electrocardiogram, e.g., EGM or ECG. QRSis usually the central and most visually obvious part of the tracing. Itcorresponds to the depolarization of the right and left ventricles ofthe human heart. In adults, deflections normally last 0.06-0.10 seconds;in children and during physical activity, it may be shorter. The Q, R,and S waves occur in rapid succession, do not all appear in all leads,and reflect a single event, and thus are usually considered together. AQ wave is any downward deflection after the P wave. An R wave follows asan upward deflection, and the S wave is any downward deflection afterthe R wave. The T wave follows the S wave, and in some cases anadditional U wave follows the T wave. The late activity is extendedafter the QRS termination and it is characterized by a fragmented anddiscrete late component. QRS represents simultaneous activation of theright and left ventricle.

In each EGM panel shown in the lower portion of FIGS. 3A, 3B and 3C, V1ECG lead, distal, proximal bipolar and unipolar signals are shown at 200mm/sec speed, from top to bottom, respectively.

The technique described herein will improve the existing process ofmanual measurements for duration map construction. The physician will nolonger need to manually move and measure the two duration calipers foreach point taken during duration map reconstruction. By using thepresent method to calculate each acquired point potential duration, thesystem can automatically annotate the ventricular EGMs duration from theonset to its offset, and automatically measure signals duration tocreate the PDM for Brugada syndrome substrate characterization.

Moreover, the process of prolonged EGMs detection and theirquantification in terms of potential duration is enhanced by the presenttechnique. This approach creates PDM with objective annotation,correctly identifying the adequate ablation target areas. The systemautomatically acquires bipolar and potential duration information by anablation and/or multielectrode mapping (MEM) catheter to speed up theprocedure. The method can be performed on two heart beats on the 2.5seconds of the mapping bipolar signal of the acquired point, and thepotential duration on the heart beat with the best positions stabilitycan be selected. This enables positions stability to be considered incalculating potential duration, which cannot be done manually.

FIGS. 4A and 4B show a PDM before and after RF ablation. FIG. 4A topshows the PDM before ablation, while FIG. 4A bottom shows an example ofprolonged and fragmented potential found in the purple area 305 (distalbipolar EGM 255 ms duration “DP-EMG”). After ablation, FIG. 4B top showsthe PDM with the disappearance of abnormally prolonged EGMs,highlighting that the late component (activation after the QRS—peaksabove 0.05 mV where Potential duration is bigger than 200 ms) has beenabolished (EGMs duration of 143 ms; FIG. 4B bottom). The asterisk inFIG. 4B bottom indicates the disappearance of the late components thathad been recorded prior to ablation. The EGM showed in FIG. 4B has beenregistered in the same region that was previously exhibiting theprolonged and fragmented potential, illustrated in FIG. 4A. In each EGMpanel, V1 II ICS ECG lead, distal, proximal bipolar, and unipolarsignals recorded are shown from top to bottom, respectively. Of note, inFIG. 4A bottom, the V1 lead is showing a typical coved-type pattern,whereas in FIG. 4B bottom, the same ECG lead is demonstrating that theBrS pattern has been modified, showing a horizontal and flat ST-segmentelevation after ablation.

FIG. 5 shows a calculation of Potential Duration which is marked by thetwo vertical lines or borders, R1 and R2. These borders indicateWOI[−50,400] from 2000 ms−50 ms (1950 ms) to 2000 ms+400 ms (2400 ms).As shown, the Potential Duration is greater than 200 ms. Around thedotted vertical line is the QRS; the late component appears in the rightpart of the Potential Duration marked with the two borders R1 and R2.

FIG. 6 shows changes in BS ECG signal, that is, the changes of the BSECG Signals 601 when the BrS is induced, and the BS ECG Signals 602after treating the BrS with ablation. Accordingly, ECG 602 refers to endof class IC drug injection and ECG 601 refers to end of RF ablation.

FIG. 7 is a work flow diagram of Brugada syndrome epicardial ablation.In step S701, endocardial bipolar/duration RV mapping is performed. Instep S702, epicardial bipolar/duration mapping is performed, creating abaseline PDM as shown, for example, in FIG. 1. In step S703, an ajmalineinfusion is administered and an ajmaline test is performed. In stepS704, an updated epicardial duration map, which maintains the FAM(anatomical volume) data and adds electro-anatomical data is produced.In step S705, it is determined whether or not there are areas ofdelimination, that is, areas in which the duration of potentials exceeda threshold amount, for example, a threshold greater than 200 ms. If so(S705=YES), in step S806 catheter ablation of the area(s) ofdelimination is performed. In step S707, the ajmaline test is repeated;this test had been initially performed in step S703.

In step S708, it is determined whether or not the BrS pattern reappears.If the BrS pattern does reappear (S708=YES), the procedure continues atstep S704. If the BrS pattern does not reappear (S708=NO), at step S709,an updated epicardial duration re-map is created. In step S710, it isdetermined whether or not any abnormal EGMs are identified. If there arenone (S710=NO), the procedure ends.

If one or more abnormal EGMs are identified (S710=YES), at step S711,catheter ablation of the new abnormal EGM areas is prepared and theprocess continues at step S709.

If the areas of delimination are less than or equal to 200 ms (S705=NO),then the procedure ends.

FIG. 8 is an illustration of an example medical system 800 that may beused to generate and display information 52 (e.g., PDM and other mapsand anatomical models of a portion of a patient and signal information).Tools, such as tool 22, can be any tool used for diagnostic ortherapeutic treatment, such as for example, a catheter having aplurality of electrodes for mapping electrical potentials in a heart 26of a patient 28. Alternatively, tools may be used, mutatis mutandis, forother therapeutic and/or diagnostic purposes of different portions ofanatomy, such as in the heart, lungs or other body organs, such as theear, nose, and throat (ENT). Tools may include, for example, probes,catheters, cutting tools and suction devices.

An operator 30 may insert the tool 22 into a portion of patient anatomy,such as the vascular system of the patient 28 so that a tip 56 of thetool 22 enters a chamber of the heart 26. The control console 24 may usemagnetic position sensing to determine 3-D position coordinates of thetool (e.g., coordinates of the tip 56) inside the heart 26. To determinethe position coordinates, a driver circuit 34 in the control console 24may drive, via connector, 44, field generators 36 to generate magneticfields within the anatomy of the patient 28.

The field generators 36 include one or more emitter coils (not shown inFIG. 8), placed at known positions external to the patient 28, which areconfigured to generate magnetic fields in a predefined working volumethat contains a portion of interest of the patient anatomy. Each of theemitting coils may be driven by a different frequency to emit a constantmagnetic field. For example, in the example medical system 800 shown inFIG. 8, one or more emitter coils can be placed below the torso of thepatient 28 and each configured to generate magnetic fields in apredefined working volume that contains the heart 26 of the patient.

As shown in FIG. 8, a magnetic field location sensor 38 is disposed atthe tip 56 of tool 22. The magnetic field location sensor 38 generateselectrical signals, based on the amplitude and phase of the magneticfields, indicating the 3-D position coordinates of the tool (e.g.,position coordinates of the tip 56). The electrical signals may becommunicated to the control console 24 to determine the positioncoordinates of the tool. The electrical signals may be communicated tothe control console 24 via wire 45.

Alternatively, or in addition to wired communication, the electricalsignals may be wirelessly communicated to the control console 24, forexample, via a wireless communication interface (not shown) at the tool22 that may communicate with input/output (I/O) interface 42 in thecontrol console 24. For example, U.S. Pat. No. 6,266,551, whosedisclosure is incorporated herein by reference, describes, inter alia, awireless catheter, which is not physically connected to signalprocessing and/or computing apparatus and is incorporated herein byreference. Rather, a transmitter/receiver is attached to the proximalend of the catheter. The transmitter/receiver communicates with a signalprocessing and/or computer apparatus using wireless communicationmethods, such as IR, RF, Bluetooth, or acoustic transmissions. Thewireless digital interface and the I/O interface 42 may operate inaccordance with any suitable wireless communication standard that isknown in the art, such as for example, IR, RF, Bluetooth, one of theIEEE 802.11 family of standards (e.g., Wi-Fi), or the HiperLAN standard.

Although FIG. 8 shows a single magnetic field location sensor 38disposed at the tip 56 of tool 22, tools may include one or moremagnetic field location sensors each disposed at any tool portion. Themagnetic field location sensor 38 may include one or more miniaturecoils (not shown). For example, a magnetic field location sensor mayinclude multiple miniature coils oriented along different axes.Alternatively, the magnetic field location sensor may comprise eitheranother type of magnetic sensor or position transducers of other types,such as impedance-based or ultrasonic location sensors.

The signal processor 40 is configured to process the signals todetermine the position coordinates of the tool 22, including bothlocation and orientation coordinates. The method of position sensingdescribed hereinabove is implemented in the CARTO™ mapping systemproduced by Biosense Webster Inc., of Diamond Bar, Calif., and isdescribed in detail in the patents and the patent applications citedherein.

The tool 22 may also include a force sensor 54 contained within the tip56. The force sensor 54 may measure a force applied by the tool 22(e.g., the tip 56 of the tool) to the endocardial tissue of the heart 26and generate a signal that is sent to the control console 24. The forcesensor 54 may include a magnetic field transmitter and a receiverconnected by a spring in the tip 56, and may generate an indication ofthe force based on measuring a deflection of the spring. Further detailsof this sort of probe and force sensor are described in U.S. PatentApplication Publications 2009/0093806 and 2009/0138007, whosedisclosures are incorporated herein by reference. Alternatively, the tip56 may include another type of force sensor that may use, for example,fiber optics or impedance measurements.

The tool 22 may also include an electrode 48 coupled to the tip 56 andconfigured to function as an impedance-based position transducer.Additionally or alternatively, the electrode 48 may be configured tomeasure a certain physiological property, for example the local surfaceelectrical potential (e.g., of cardiac tissue) at one or more locations.The electrode 48 may be configured to apply RF energy to ablateendocardial tissue in the heart 26.

Although the example medical system 800 may be configured to measure theposition of the tool 22 using magnetic-based sensors, other positiontracking techniques may be used (e.g., impedance-based sensors).Magnetic position tracking techniques are described, for example, inU.S. Pat. Nos. 5,391,199, 5,443,489, 6,788,967, 6,690,963, 5,558,091,6,172,499 6,177,792, the disclosures of which are incorporated herein byreference. Impedance-based position tracking techniques are described,for example, in U.S. Pat. Nos. 5,983,126, 6,456,828 and 5,944,022, thedisclosures of which are incorporated herein by reference.

The I/O interface 42 may enable the control console 24 to interact withthe tool 22, the body surface electrodes 46 and any other sensors (notshown). Based on the electrical impulses received from the body surfaceelectrodes 46 and the electrical signals received from the tool 22 viathe I/O interface 42 and other components of medical system 900, thesignal processor 40 may determine the location of the tool in a 3-Dspace and generate the display information 52, which may be shown on adisplay 50.

The signal processor 40 may be included in a general-purpose computer,with a suitable front end and interface circuits for receiving signalsfrom the tool 22 and controlling the other components of the controlconsole 24. The signal processor 40 may be programmed, using software,to perform the functions that are described herein. The software may bedownloaded to the control console 24 in electronic form, over a network,for example, or it may be provided on non-transitory tangible media,such as optical, magnetic or electronic memory media. Alternatively,some or all of the functions of the signal processor 40 may be performedby dedicated or programmable digital hardware components.

In the example shown at FIG. 8, the control console 24 is connected, viacable 44, to body surface electrodes 46, each of which are attached topatient 28 using patches (e.g., indicated in FIG. 8 as circles aroundthe electrodes 46) that adhere to the skin of the patient. Body surfaceelectrodes 46 may include one or more wireless sensor nodes integratedon a flexible substrate. The one or more wireless sensor nodes mayinclude a wireless transmit/receive unit (WTRU) enabling local digitalsignal processing, a radio link, and a miniaturized rechargeablebattery. In addition or alternative to the patches, body surfaceelectrodes 46 may also be positioned on the patient using articles wornby patient 28 which include the body surface electrodes 46 and may alsoinclude one or more position sensors (not shown) indicating the locationof the worn article. For example, body surface electrodes 46 can beembedded in a vest that is configured to be worn by the patient 28.During operation, the body surface electrodes 46 assist in providing alocation of the tool (e.g., catheter) in 3-D space by detectingelectrical impulses generated by the polarization and depolarization ofcardiac tissue and transmitting information to the control console 24,via the cable 44. The body surface electrodes 46 can be equipped withmagnetic location tracking and can help identify and track therespiration cycle of the patient 28. In addition to or alternative towired communication, the body surface electrodes 46 may communicate withthe control console 24 and one another via a wireless interface (notshown).

During the diagnostic treatment, the signal processor 40 may present thedisplay information 52 and may store data representing the information52 in a memory 58. The memory 58 may include any suitable volatileand/or non-volatile memory, such as random access memory or a hard diskdrive. The operator 30 may be able to manipulate the display information52 using one or more input devices 59. Alternatively, the medical system800 may include a second operator that manipulates the control console24 while the operator 30 manipulates the tool 22. It should be notedthat the configuration shown in FIG. 8 is exemplary. Any suitableconfiguration of the medical system 800 may be used and implemented.

FIG. 9 is a block diagram illustrating example components of a medicalsystem 900 in which features described herein can be implemented. Asshown in FIG. 9, the system 900 includes catheter 902, processing device904, display device 906 and memory 912. As shown in FIG. 9, theprocessing device 904, display device 906 and memory 912 are a part ofcomputing device 914. In some embodiments, the display device 906 may beseparate from computing device 914. Computing device 914 may alsoinclude an I/O interface, such as I/O interface 42 shown in FIG. 9.

Catheter 902 includes a plurality of catheter electrodes 908 fordetecting the electrical activity of the heart over time. Catheter 902also includes sensor(s) 916, which include, for example, sensors (e.g.,a magnetic field location sensor) for providing location signals toindicate the location of the catheter 902 in a 3-D space as well assensors (e.g., position sensors, pressure or force sensors, temperaturesensors, impedance sensors) for providing ablation parameter signalsduring the ablation of the heart tissue. The example system 900 alsoincludes one or more additional sensors 910, separate from the catheter902, used to provide location signals indicating the location of thecatheter 902 in a 3D space.

The system 902 shown in example system 900 also includes an RF generator918, which supplies high-frequency electrical energy, via catheter 902,for ablating tissue at locations engaged by the catheter 902.Accordingly, catheter 902 may be used to acquire electrical activity forgenerating mapping of the heart as well ablating cardiac tissue. Asdescribed above, however, embodiments may include catheters used toacquire the electrical activity for generating mapping of the heartwhile not used to ablate cardiac tissue.

Processing device 904 may include one or more processors each configuredto process the ECG signals, record ECG signals over time, filter ECGsignals, fractionate ECG signals into signal components (e.g., slopes,waves, complexes) and generate and combine ECG signal information fordisplaying the plurality of electrical signals on display device 906.Processing device 904 may also generate and interpolate mappinginformation for displaying maps of the heart on display device 906.Processing device 904 may include one or more processors (e.g., signalprocessor 40) configured to process the location information acquiredfrom sensors (e.g., additional sensor(s) 910 and catheter sensor(s) 916)to determine location and orientation coordinates.

Processing device 904 is also configured to drive display device 906 todisplay dynamic maps (i.e., spatio-temporal maps) of the heart and theelectrical activity of the heart using the mapping information and theECG data. Display device 906 may include one or more displays eachconfigured to display maps of the heart representing spatio-temporalmanifestations of the electrical activity of the heart over time anddisplay the ECG signals acquired from the heart over time.

The catheter electrodes 908, catheter sensor(s) 916 and additionalsensor(s) 910 may be in wired or wireless communication with processingdevice 904. Display device 906 may also be in wired or wirelesscommunication with processing device 904.

The methods provided can be implemented in a general purpose computer, aprocessor, or a processor core. Suitable processors include, by way ofexample, a general purpose processor, a special purpose processor, aconventional processor, a digital signal processor (DSP), a plurality ofmicroprocessors, one or more microprocessors in association with a DSPcore, a controller, a microcontroller, Application Specific IntegratedCircuits (ASICs), Field Programmable Gate Arrays (FPGAs) circuits, anyother type of integrated circuit (IC), and/or a state machine. Suchprocessors can be manufactured by configuring a manufacturing processusing the results of processed hardware description language (HDL)instructions and other intermediary data including netlists (suchinstructions capable of being stored on a computer readable media). Theresults of such processing can be maskworks that are then used in asemiconductor manufacturing process to manufacture a processor whichimplements features of the disclosure.

The methods or flow charts provided herein can be implemented in acomputer program, software, or firmware incorporated in a non-transitorycomputer-readable storage medium for execution by a general purposecomputer or a processor. Examples of non-transitory computer-readablestorage mediums include a read only memory (ROM), a random access memory(RAM), a register, cache memory, semiconductor memory devices, magneticmedia such as internal hard disks and removable disks, magneto-opticalmedia, and optical media such as CD-ROM disks, and digital versatiledisks (DVDs).

An example study employing the present method is presented. In thisexample study, a patient population is obtained comprising consecutiveselected symptomatic patients diagnosed with type 1 BrS-ECG patterneither spontaneously or after ajmaline administration; each patient alsohad an ICD implanted. Ajmaline administration (1 mg/Kg in 5 minutes) wasconsidered positive if the typical coved-type ECG pattern appeared inmore than one right precordial lead (V1-V3).

Patients underwent a combined epi-endocardial mapping procedure(examples of mapping shown in FIGS. 10-15, described below). Undergeneral anesthesia, an invasive arterial pressure line was obtainedthrough radial artery access. The ECG was continuously recorded duringthe procedure. After femoral venous access, a multipolar diagnosticcatheter was positioned at the RV apex. The epicardial access was gainedby a percutaneous subxyphoid access to the pericardial space, as isknown in the art. Three dimensional RV endocardial and epicardialmapping, using CARTO® 3, was performed in all patients during stablesinus rhythm and presence of type 1 BrS-ECG pattern. Epicardial mappingwas systematically performed after endocardial mapping, in order to haveadequate delimination of the RV boundaries when mapping the epicardium.Epicardial RV mapping and ablation catheter manipulation were assistedby a steerable sheath, such as Agilis EPI, St. Jude Medical, St. Paul,Minn. BrS epicardial substrate identification consisted in mapping theentire RV epicardial surface under baseline conditions and afterajmaline infusion (imp/Kg in 5 minutes). Three groups of RV epicardialelectrograms properties are obtained using a CARTO® 3 mapping system: 1)bipolar/unipolar voltage map, 2) local activation time map (LAT), and 3)potential duration map (PDM) in which abnormal long-duration bipolarelectrograms were defined as low-frequency (up to 100 Hz) prolongedduration (>200 ms) bipolar signals with delayed activity extendingbeyond the end of the QRS complex. FIGS. 10-12, which are describedbelow, illustrate this. The bipolar electrograms were filtered from 16Hz to 500 Hz, displayed at a speed of 200 ms and were recorded betweenthe distal electrode pair. Electrograms were excluded if their technicalquality was insufficient or if catheter-induced extrasystoles occurred.

Voltage mapping, in this example study is described as follows.Color-coded electroanatomical voltage (not shown), activation (notshown) and duration maps (shown in FIG. 10A, 10B, 10C using various hashpatterns to indicate various colors) were performed and superimposed tocardiac anatomy. Red color 1003 indicates low-voltage dense scar thatarbitrarily was defined as bipolar signal amplitude <0.5 mV, whilepurple color 1001 indicates voltage areas >1.5 mV. Areas of low voltagewere identified using standard voltage cut-off values for dense scar(<0.5 mV) and border zone (BZ) (<1.5 mV). Electrograms below the 0.05 mVthreshold were not considered.

LAT mapping in this example study is described as follows. To studyactivation, the local activation time was assessed, defined as theinterval (in milliseconds) from a peak of QRS in lead II to the steepestnegative change in voltage over time (dV/dt) of the intrinsic deflectionin the bipolar electrogram. Activation-duration was defined as theinterval (in milliseconds) between the earliest activation time of anyelectrogram (activation-start) and the latest activation time of anyelectrogram (activation-end).

Potential Duration Mapping (PDM) in this example study is described asfollows. The maximum electrogram duration was the longest electrogramwith continuous deflections without an intervening isoelectric line asrecorded with a 0.45 sec window of interest (WOI). Fractionation ofelectrograms was defined as the presence of more than two intrinsicdeflections and expressed as number of intrinsic deflections perelectrogram. Electrogram duration was measured before and after ajmalinein the bipolar signal as the interval between the onset of the first andthe offset of the last component of the electrogram, measured at thetime scale of 200 mm/sec, and expressed as mean bipolar electrogramduration (in milliseconds). A cut-off range from 100 ms to 200 ms, 250ms and 280 ms was used for defining color-coded duration maps. As aresult, a color-code map was obtained showing the regions displaying theshortest (<110 ms cut-off, red 1003) and the longest duration (>200 mscut-off, purple 1001), respectively. The degree of duration of thepotentials was displayed from the longest (purple 1001) to the shortestpotential (red 1003) using different duration cut-off values(illustrated in FIGS. 10-14). According to the selected cut-offs, threedifferent concentric circles were drawn around purple areas as shown inFIG. 11. The PDM was performed by collecting the duration of eachbipolar electrogram using the CARTO® 3 system.

Substrate-based ablation in this example study is described as follows.Epicardial ablation was performed during sinus rhythm using a stepwisestrategy in a descending order of abnormal potential duration asdisplayed on the map and beginning from the longest potentials. Thelongest-duration potential area was displayed in purple by setting thecolor-bar upper limit (300 ms) in the three-dimensional duration map, ascreated simultaneously during voltage and LAT mapping. Afterwards, RFablation was performed sequentially by gradually moving at substratesites towards areas with less prolonged late (250 ms and 200 ms)potentials according to the stepwise strategy. RF was delivered with anexternally irrigated 3.5 mm tip ablation catheter. A power control modehaving from 35 W up to 45 W was used. The irrigation rate was 17 mL/minfor RF ablation, which was delivered by a dragging strategy, up tocomplete elimination of all long-duration, delayed activity.

FIG. 15 shows BrS-ECG pattern changes during epicardial RF ablation thatwere analyzed by continuous ECG monitoring. The ST-segment modificationswere evaluated using a correlation software, such as PASO in CARTO® 3.Immediate ablation endpoint was the elimination of all abnormallyprolonged late activity with normalization of BrS-ECG pattern, as shownin FIG. 15.

Ajmaline was systematically re-infused after RF ablation to ensureabolition of all abnormal ventricular potentials while confirming theBrS-ECG pattern elimination. In patients in whom the BrS-ECG patternreappeared during infusion, epicardial duration maps were repeated toidentify any residual or additional abnormal signals for further RFapplications in order to definitively normalize the ECG pattern. Once astable BrS-ECG pattern elimination was obtained, VT/VF inducibility wasassessed. Intrapericardial liquid was permanently withdrawn through thedeflectable sheet during the procedure to avoid serum accumulation.

The end-point of the example study was elimination of all abnormalelectrical ventricular potentials before and after ajmaline, leading toECG normalization and non-inducibility of ventricular tachycardia (VT)with respect to ventricular fibrillation (VF), e.g., VT/VF.

BrS was diagnosed in the presence of a coved-type ST elevation of >2 mmas documented in more than one lead from V1 to V3 positioned in thesecond, third, or fourth intercostal space. Because of the variablenature of the BrS-ECG pattern, BrS patients were classified according totheir ECG at the time of the presentation and defined as spontaneous ECGpattern. Three BrS patient groups (BrS-1 to BrS-3) were defined ascoved-type (BrS-1), saddleback ST configuration (BrS-2), and either type1 or type 2 but with <2 mm of ST segment elevation (BrS-3). BrS patientswith typical BrS-related symptoms included those with documented VF orpolymorphic VT at the time of symptoms. BrS patients without typicalBrS-related symptoms were considered as patients with different symptoms(from dizziness to palpitations) without ECG documentation at the timeof events but all with inducible VT/VF. Patients with the worst clinicalpresentation were defined as those who experienced cardiac arrest orsyncope due to documented ventricular fibrillation. A proband wasdefined as the first patient diagnosed with Brugada syndrome in a familyon the basis of a type 1 Brugada ECG pattern. Major complications weredefined as those that required prolonged hospitalization.

Procedural data in the example study include the following. The medianprocedure, fluoroscopy and RF application times were 169 minutes(Inter-quartil (IQR) 160-214, min-max 105-266), 8 minutes (IQR 7-9,min-max 6-14) and 18 minutes (IQR 17-21, min-max 12-31), respectively.During the procedure, the activation, voltage and duration maps weresuccessfully acquired during sinus rhythm and after ajmaline-inducedtype 1 BrS-ECG pattern in all patients. At baseline, epicardialactivation started in the lower septum/apex and subsequently divergedtoward the tricuspid annulus and RVOT. As shown in FIGS. 10-14, forexample, the red areas indicate short activation times while blue areasindicate longer activation times. No apparent conduction block wasobserved in any patient. After ajmaline infusion, the epicardialactivation time was slightly longer without change in the sequenceactivation pattern, but this difference was not statisticallysignificant, as shown in the table in FIG. 16. Overall,electro-anatomical voltage maps showed very small low-voltage areas inRVOT, which were larger in Group 1, particularly in patients with theworst clinical presentation than in Group 2 (P<0.001 as shown in FIG.16). Before and after ajmaline, 3D epicardial duration maps displayedlarge areas of variable size with abnormally prolonged potentials in theRVOT, which contrasted with normal signals in the surrounding areas.

Electrophysiological substrate characteristics according to spontaneousECG pattern in the example study are as follows. Baseline clinical andECG characteristics did not differ between the two groups includingpatients with the worst clinical presentation; spontaneous type 1BrS-ECG pattern was less frequently found regardless of clinicalpresentation, as shown in the table in FIG. 17. CARTO® 3 maps identifiedepicardial areas of abnormal prolonged electrical signals over the RVOT(>75%) extending after ajmaline to RV free wall (see FIGS. 10-14). Thearea of electrical substrate significantly increased in size afterajmaline in both groups as shown in the table in FIG. 16. Before andafter ajmaline, Group 1 showed wider area and more prolonged andabnormal potentials than Group 2, although the increase in Group 2 wasthree times higher as compared with baseline values shown in the tablein FIG. 16. Of note, regardless of clinical presentation, before andafter ajmaline the epicardial electrical substrate was larger in menthan women. Areas with the longest abnormal potentials (>280 ms) indifferent RV regions appeared on color-coded maps to be smaller,displaying a characteristic onion-like substrate of concentric circlesshowing in the center of the area with the widest electrograms (see FIG.11).

Electrophysiological substrate characteristics according to spontaneousECG pattern in the example study are described as follows. There was nodifference in clinical characteristics between patients with and withoutspontaneous type 1 ECG pattern including age, sex, or family history ofsudden death of those less than 45 years old. Large abnormal areas andwider abnormal electrograms were found in patients with type 1 ECGpattern than in patients without. The localization of abnormal areas didnot differ between patients with and without type 1 ECG pattern.Baseline ST segment elevation did not differ between Group 1 and Group2, but after ajmaline the increase was significantly higher in Group 1.Overall, after ajmaline the degree of type 1 ST-segment elevationcorrelated with the magnitude of the wider area (r=0.682, p<0.001).

Substrate-based epicardial ablation in the example study can bedescribed as follows. Once the areas targeted for ablation wereestablished on the map of electrogram duration, RF started beginning onareas with the widest electrical potentials, which during ablationdisappeared without significant change in voltage-amplitude after RF wasturned off. Elimination of abnormal signals was confirmed by remap andajmaline reinfusion. Seventy-eight patients after ajmaline reinfusionshowed reappearance of suspicious coved ECG pattern requiring further RFablation to eliminate any residual abnormal potentials. Ablation atthese sites eliminated the type 1 ECG pattern with successfulsuppression of VT/VF. Characteristically, during initial delivery of RFenergy on the longest potential duration areas, the type 1 ECG patternincreased for some seconds, to progressively invert the ST segment slopefrom descending to ascending (see FIG. 12), and the increase was higherin Group 1. Immediately after, there was a typical flat ST-segmentelevation progressively becoming ascendant in V1 and V2, which was notfurther modified by ajmaline and isoproterenol infusion.

FIGS. 10-17 illustrate the example study. Note that different hatchingpatterns are used to show different colors, e.g., color-coding, in FIGS.10-15. FIGS. 10 and 11 illustrate a 39-year-old Brugada Syndrome (BrS)patient, presenting with a family history of BrS and syncope, who had anICD implantation. The patient had positive ajmaline test and VT/VFinducibility during an electrophysiological study.

FIG. 10A shows baseline BrS-ECG pattern and epicardial color-codedduration CARTO® maps. A saddle-back pattern is evident in V2 (IIintercostal space) with a corresponding small (2.2 cm²) purple area 1001of abnormally prolonged potentials (210 ms in the example). Theborder-zone area (green/blue area 1002 greater than 110 ms and less than200 ms) shows potentials with relatively shorter duration (136 ms).

FIG. 10B shows BrS-ECG pattern and color-coded duration maps afterajmaline. After type 1 ajmaline-induced ECG pattern, the abnormal purplearea 1001 significantly increased to 21.5 cm². Examples of abnormal andprolonged electrograms (EGMs) found in the purple area 1001 afterajmaline test are shown beside the map (289 ms and 219 ms).

FIG. 10C shows BrS-ECG pattern and color-coded duration maps after RFablation of epicardial substrate. After ajmaline re-challenge at the endof the procedure, the ECG showed a horizontal and ascendant ST-segmentelevation, with minimal intraventricular conduction delay characterizedby slight QRS broadening with a more pronounced S wave in leads I and IIand qR morphology in a VII. Abnormally prolonged fragmented and delayedEGMs disappeared (87 ms and 96 ms, light-blue color 1004).

The two examples of ventricular EGMs shown on the right side of FIGS.10A, 10B and 10C (one above the other) were recorded from the previouslyabnormal area, and the red asterisks indicate disappearance of the latecomponents. The two EGM panels in each of FIGS. 10A, 10B and 10C arefrom the CARTO® 3 system and each ECG panel shows V2 ECG lead (top),distal (second from top), proximal bipolar (third from top) and unipolar(bottom) signals at a speed of 200 ms. Of note, in FIG. 10B, V2 leadshows a typical coved-type pattern, which after ablation was modifiedinto a horizontal and flat ST-segment elevation.

FIG. 11 shows a Potential Duration Map and Concentric ‘Onion-like’Substrate. This is the same patient as in FIG. 10. The epicardial mapshows a concentric ‘onion-like’ substrate distribution after ajmaline.White lines delimitate multiple areas exhibiting electrograms (EGMs)with different duration (≥300 panel A, ≥250 panel B, and ≥200 ms panelC). Areas with the longest potential duration (≥300 ms) are in the innercircle (panel A), while relatively shorter areas (≥250 and ≥200 ms) arein the outer circle (panels B and C). In FIG. 11, red regions 1101represent areas with EGM potential duration ≤110 ms. Below each map,there is an example of the EGM recorded in the purple area 1102 (320 msduration in panel A, 264 in B and 225 in C, respectively). Each EGMpanel from the CARTO® system shows V2 ECG lead (top), distal (secondfrom top), proximal bipolar (third from top) and unipolar (bottom)signals at speed of 200 ms speed.

FIG. 12 shows spontaneous type 1 Brugada pattern. The figure refers to a32-year old patient with spontaneous type 1 Brugada pattern implantedwith an ICD due to history of frank syncope without prodromes and anelectrophysiological study (EPS) positive for VT/VF induction. In theleft panel, the 12-lead ECG with precordial leads placed in V1 and V2 athigher intercostal spaces (II, III and IV ICS) shows typical type 1Brugada pattern particularly evident in V1 and V2 II ICS and in V1 IIIICS. The middle panel of FIG. 12, shows the epicardial PDM in which thepurple area 1201 exhibits long duration potentials (≥200 ms; dimensions21.5 cm²). The two right panels show two examples of electrograms (EGMs)found in the most fragmented and prolonged region (purple area 1201). Ofnote, typical EGM of wide duration with low voltage and fragmenteddelayed components are shown in the distal bipolar (second line fromtop) signal, 320 and 280 ms duration, respectively). In each EGM panel,V1 and V2 II ICS ECG lead (top), distal (second from top), proximalbipolar (third from top) and unipolar (bottom) signals are shown atspeed of 200 ms.

FIG. 13 shows RF ablation in spontaneous type 1 Brugada pattern, usingthe same patient as in FIG. 12. The top left panel shows the PDM withwhite circles 1301 delimitating the areas exhibiting potentials duration≥300 ms (inner circle) and ≥200 ms (outer circle). RF ablation in theinner circle (red dots 1302) determined initial ascending and horizontalST-segment elevation in the high right precordial leads, shown in thetop panel on the right, box 1303. In the left bottom panel, the completeset of lesions has been delivered in the whole area ≥200 ms resulting inpersistent horizontal and flat ST elevation in the right precordialleads, which are not showing the Brugada type 1 pattern at the end ofablation (right bottom panel, red box 1303).

FIG. 14 shows a PDM before and after RF ablation, using the same patientas in FIG. 12. The left-top panel shows the PDM before ablation. Theleft-bottom panel shows an example of a wide and fragmented potentialdiscovered in the purple area 1401 (distal bipolar EGM 320 ms duration).After ablation, the PDM in the right-top panel shows the disappearanceof abnormally prolonged EGMs, highlighting that the late component hasbeen abolished by ablation (EGM duration 69 ms, right-bottom panel, redasterisk). The EGM showed in the right-bottom panel has been recorded inthe same region that had previously exhibited the prolonged andfragmented potential illustrated in the left-bottom panel. The ablationcatheter shadow in both CARTO® maps indicates the location where suchpotentials have been recorded. In each EGM panel, (bottom left andright) V2 II ICS ECG lead (top), distal (second from top), proximalbipolar (third from top) and unipolar (bottom) signals are shown atspeed of 200 ms. Of note, in the left-bottom panel, the V2 lead isshowing typical coved-type pattern, whereas in the right-bottom panel,the same ECG lead is demonstrating that the Brugada pattern has beenmodified, showing a horizontal and flat ST segment elevation afterablation.

FIG. 15 shows ECG changes immediately after ablation and thirteen monthsfollowing the procedure, using the same patient as in FIG. 12. The toppanel shows the acute disappearance of the type 1 pattern after RFablation of the area showing fragmented and prolonged potentials. On theleft, the baseline Brugada ECG is followed by the disappearance of thetype 1 pattern immediately after ablation (top-middle panel), proved bythe final ajmaline challenge repeated at the end of the procedure(top-right panel). The high right precordial leads show horizontal andflat ST-segment elevation that disappears during the follow-up (bottompanel). The bottom panel shows the persistent disappearance of Brugadatype 1 pattern, proved by ajmaline challenge thirteen months afterablation. Ajmaline infusion determines PR interval prolongation with QRSbroadening and slight ST segment horizontal elevation without themorphological characteristics of the coved-type ECG. From left to right,baseline 12-leads ECG, ECG with high right precordial leads at baselineand after ajmaline administration are shown.

It will be appreciated by persons skilled in the art that the presentteachings are not limited to what has been particularly shown anddescribed herein. Instead, the scope of the present teachings includeboth combinations and sub-combinations of the various features describedherein, as well as variations and modifications thereof that are not inthe prior art, which would occur to persons skilled in the art uponreading the foregoing description.

What is claimed is:
 1. A computer implemented method for determiningtarget ablation areas of a heart, comprising: acquiring, over time,electrical signals for a plurality of areas of the heart; and generatingan epicardial potential duration map for display by: calculating, foreach electrical signal, a plurality of heart beats based on a heart beatcycle length and a reference point in time of one of the heart beats;assigning, for each heart beat of an electrical signal, a window ofinterest (WOI) equal to an amount of time comprising at least the heartbeat cycle length; for each WOI: determining a start potential durationand an end potential duration; calculating a potential duration value asthe difference between the start potential duration and the endpotential duration; and selecting the potential duration based on thepotential duration values, wherein, when a selected potential durationof an electrical signal is greater than or equal to a potential durationthreshold, the area of the heart corresponding to the electrical signalis targeted for ablation.
 2. The method according to claim 1, whereingenerating the epicardial potential duration map further comprisesdetermining another reference point in time of a prior heart beataccording to an amount of time from the reference point in time equal tothe heart beat cycle length; and the prior heart beat is calculatedbased on the heart beat cycle length and the other reference point intime.
 3. The method according to claim 1, further comprising: performingepicardial ablation on the areas of the heart targeted for ablation;after performing the epicardial ablation, preparing an updatedepicardial Potential duration map and determining whether the updatedepicardial potential duration map includes a displayed abnormality; andwhen the updated epicardial potential duration map includes theabnormality, performing another epicardial ablation on an area of theheart corresponding to the displayed abnormality.
 4. The methodaccording to claim 1, wherein the potential duration threshold is 200ms.
 5. The method according to claim 1, further comprising determiningthe start potential duration and the end potential duration for theepicardial potential duration map by determining peaks in the WOI whichare equal to or greater than a peak threshold and identifying the startpotential duration as the start of the slope before a first determinedpeak and identifying the end potential duration as a second determinedpeak having a distance greater than or equal to 120 ms from the firstdetermined peak.
 6. The method according to claim 1, further comprising:Performing epicardial ablation on the area of the heart targeted forablation; and after performing the epicardial ablation, preparing anupdated epicardial potential duration map, wherein the epicardialpotential duration map, and the updated epicardial potential durationmap include displayed concentric areas having a plurality of differentcut-off intervals.
 7. A system for determining target ablation areas ina heart, comprising: a catheter for acquiring electrical signals for aplurality of areas of the heart; one or more processors configured to:generate an epicardial potential duration map for display by:calculating, for each electrical signal, a plurality of heart beatsbased on a heart beat cycle length and a reference point in time of oneof the heart beats; assigning, for each heart beat of an electricalsignal, a window of interest (WOI) equal to an amount of time comprisingat least the heart beat cycle length; for each WOI: determining a startpotential duration and an end potential duration; calculating apotential duration value as the difference between the start potentialduration and the end potential duration; and selecting the potentialduration based on the potential duration values, wherein, when aselected potential duration of an electrical signal is greater than orequal to a potential duration threshold, the area of the heartcorresponding to the electrical signal is targeted for ablation; and adisplay device for displaying the epicardial potential duration map. 8.The system according to claim 7, the one or more processors are furtherconfigured to: generate the epicardial potential duration map; bydetermining another reference point in time of a prior heart beataccording to an amount of time from the reference point in time equal tothe heart beat cycle length; and the prior heart beat is calculatedbased on the heart beat cycle length and the other reference point intime.
 9. The system according to claim 7, the one or more processors arefurther configured to: control the catheter to perform epicardialablation on the areas of the heart targeted for ablation; afterperforming the epicardial ablation, prepare an updated epicardialpotential duration map and determine whether the updated epicardialpotential duration map includes a displayed abnormality; and when theupdated epicardial potential duration map includes the displayedabnormality, perform another epicardial ablation on an area of the heartcorresponding to the displayed abnormality.
 10. The system according toclaim 7, wherein the potential duration threshold is 200 ms.
 11. Thesystem according to claim 7, the one or more processors are furtherconfigured to, determine the start potential duration and the endpotential duration for the epicardial potential duration map bydetermining peaks in the WOI which are equal to or greater than a peakthreshold and identifying the start potential duration as the start ofthe slope before a first determined peak and identifying the endpotential duration as a second determined peak having a distance greaterthan or equal to 120 ms from the first determined peak.
 12. The systemaccording to claim 7, wherein the one or more processors are furtherconfigured to: control the catheter to perform epicardial ablation onthe area of the heart targeted for ablation; and after performing theepicardial ablation, prepare an updated epicardial Potential durationmap, wherein at least one of the epicardial potential duration map, andthe updated epicardial potential duration map include displayedconcentric areas having a plurality of different cut-off intervals. 13.A non-transitory computer readable storage medium comprisinginstructions for causing a computer to execute a method of determiningtarget ablation areas of a heart, the instructions comprising:acquiring, over time, electrical signals for a plurality of areas of theheart; and generating an epicardial potential duration map for displayby: calculating, for each electrical signal, a plurality of heart beatsbased on a heart beat cycle length and a reference point in time of oneof the heart beats; assigning, for each heart beat of an electricalsignal, a window of interest (WOI) equal to an amount of time comprisingat least the heart beat cycle length; for each WOI: determining a startpotential duration and an end potential duration; calculating apotential duration value as the difference between the start potentialduration and the end potential duration; and selecting the potentialduration based on the potential duration values, wherein, when aselected potential duration of an electrical signal is greater than orequal to a potential duration threshold, the area of the heartcorresponding to the electrical signal is targeted for ablation.
 14. Thecomputer readable storage medium according to claim 13, the instructionsfurther comprising: generating the epicardial potential duration map bydetermining another reference point in time of a prior heart beataccording to an amount of time from the reference point in time equal tothe heart beat cycle length; and the prior heart beat is calculatedbased on the heart beat cycle length and the other reference point intime.
 15. The computer readable storage medium according to claim 13,the instructions further comprising: performing epicardial ablation onthe areas of the heart targeted for ablation; after performing theepicardial ablation, preparing an updated epicardial potential durationmap and determining whether the updated epicardial potential durationmap includes a displayed abnormality; and when the updated epicardialpotential duration map includes the abnormality, performing anotherepicardial ablation on an area of the heart corresponding to thedisplayed abnormality.
 16. The computer readable storage mediumaccording to claim 13, the instructions further comprising determiningthe start potential duration and the end potential duration for theepicardial potential duration map by determining peaks in the WOI whichare equal to or greater than a peak threshold and identifying the startpotential duration as the start of the slope before a first determinedpeak and identifying the end potential duration as a second determinedpeak having a distance greater than or equal to 120 ms from the firstdetermined peak.
 17. The computer readable storage medium according toclaim 13, the instructions further comprising: performing epicardialablation on the area of the heart targeted for ablation; and afterperforming the epicardial ablation, preparing an updated epicardialpotential duration map, wherein the epicardial potential duration map,and the updated epicardial potential duration map include displayedconcentric areas having a plurality of different cut-off intervals.